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How do you measure dynamics?

Discussion in 'Archived Threads 2001-2004' started by Manuel Delaflor, Apr 29, 2002.

  1. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    I have read countless times about Dynamics and Microdynamics. Im very interested in that characteristic and want to know more about how is it measured or if it can be measured at all.

    Thanks!
     
  2. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    I find rather interesting that no one replied... [​IMG]
     
  3. Michael Roderiques

    Michael Roderiques Stunt Coordinator

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    Perhaps the question was asked in a way that most did not understand it.

    I have look at it and have to say I am not sure what you are asking.
     
  4. Brian OK

    Brian OK Supporting Actor

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    ears
     
  5. Lewis Besze

    Lewis Besze Producer

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    Dynamics= the difference between the loudest and softest passages,mesured in[you've guessed it[​IMG]]in db.
    Microdynamics=ask one of those "audiophiles"[​IMG]
     
  6. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    Got it, I assumed I was using common descriptions. Lewis already told what Dynamics are, micro dynamics would be more like the little changes that are present in some instrument, say a flute, when another instrument in the background is making a louder noise.

    Is there a way to measure that?
     
  7. Henry_W

    Henry_W Stunt Coordinator

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    Lewis has it on the Dynamics - I had this same question quite some time back. What I wanted to hear was the 'crisp' dynamics - that means I do not want the triangle to be drowned out by the trumpet. Apparently, refractions and reflections have so much to do with dynamics that measuring this in anything other than an absolutely perfect chamber is significantly flawed.

    I think that is why anything other than using your ears doesn't work very well. However, if you get a CD with the passage that best defines dynamics to you and audition speakers with that passage, you will be able to find some startling differences out there in how speakers handle this (good dynamics is usually usually in the higher end stuff, but surprising it is not always a prerequiste for some very expensive speakers).

    If you really want to get into an internal disagreement, try letting your ears measure how quickly a speaker can handle dynamic changes. That is another question that folks treat like a virus...
     
  8. Jeff Ery

    Jeff Ery Stunt Coordinator

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    O.k ,I'l say it and start the heat...Efficiancy!!!!
     
  9. Henry_W

    Henry_W Stunt Coordinator

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    I'll go there - the starting point for all speakers that I have heard that handle dymanics and rapid changes in the source is efficiency. Specifically, to match what I like to hear, speakers above 96db are most effective. Then, of course, with high efficiency comes a greater demand for equipment matching and the downward spiral your addiction deepens. Good money chasing bad becomes the norm (and you convince yourself that is not a problem - you can quit anytime - yeah right).

    That said - not all high efficiency speakers matched my ears (crossover settings?) and not all lower efficiency speakers were crap on dynamics. I do need to note that I have not been able to hear what I like in the rapid change area with any single driver system auditioned.

    Yep - that usually means horns and is often accompanied by bleeding ear comments. Such is the life.

    Remember to be careful out there - a twelve step program doe not exist for this addiction.
     
  10. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    I don't think efficiency entirely dictates dynamics but it certainly makes sense that it would have a big impact, especially on the ability to play very weak noises in a track to contrast with others.
    But take this example: If a weak signal and strong signal both get played by an efficient speaker, it would make the weak signal loud and the strong signal loud. Take the same and output it through an inefficient speaker and the weak signal is quiet but so is the loud signal. The result is no increase in dynamics, but simply a change in average SPL which can be matched with the increase in amplification of the inefficient speaker.
    So dynamics is the BIG changes in volume.
    Microdynamics are the subtle changes in volume.
    So do you care if the pitch changes with the dynamics of a speaker? Are you asking a way to test a sub's ability to "refresh" from loud to soft and compare it to other subs?
    A crude test could be to find test tones that sound like rapid firing bursts of noise that shift from silence to loud. The closer the bursts of sound are to each other (time wise) the harder it will be for the sub to mimic the sound. A heavy driver with weak magnets may take a while to recover while a very light diaphragm with big magnets can refresh quicker and change transients (short noises) faster.
    The difference could be one sub sounding like a constant "virtual" pitch while the other sounding like rapid individual pitchs. The one with the individual pitches would then have more dynamics than the other which blends the sounds together.
    As for microdynamics... I think an efficient speaker may be able to reveal sound that is not audible in inefficient speakers thus creating more microdynamics.
    A test for this could be playing very very quiet signals into a speaker when the volume is maxed. The speaker that is able to play more notes could perhaps be described as having a wider range for micro dynamics because it is capable of playing more from a given signal than the other speaker. (There will be minor changes in sound that don't exist in inefficient speakers that are unable to produce the soft sounds in the first place)
    I'm new to this dynamic thing I didn't even know what it was until reading this thread so these are just my assumptions.
    EDIT: Gosh, it must be getting late because I confuse even myself, I wouldn't be suprised if what I wrote makes no sense. Official time is 8:19AM which means I need to sleep if I am to wake up at 1:00PM tomorrow to see a movie with my friend. (Jackass) [​IMG]
    Please post more on this subject, i'm interested to learn how to test for dynamics as well.
     
  11. Michael R Price

    Michael R Price Screenwriter

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    How about this: If you can precisely control the input level of your amplifier (via a good volume control, or through a computer or something): Play a sound (pink noise or something) at 70db. Then increase the volume setting on your preamp in 5db steps and see if the actual sound output increases in 5db steps. As compression comes into play, the output level will not increase linearly with input.

    I haven't tried this experiment but I can imagine that with a lot of popular speakers the results would be... surprising. If you used some different frequencies including low bass... it would be very interesting

    More efficient speakers tend to have better dynamics, in part because the voice coils don't exhibit as much thermal compression (lower power input for given SPL) and that such speakers generally use larger/multiple drivers, or horns.
     
  12. Chris Tsutsui

    Chris Tsutsui Screenwriter

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    Ok, I understand that point, I forgot about compression..

    So pink noise, is simply sound that has equal energy at every octave. When putting that through a speaker I don't see how it can measure dynamics. Pink noise is overlapped sounds.. so picture layers of sound on top of eachother. Dynamics would be time based and lineal which involves playing one sound, and then another, and then changing to another (With different volumes).

    I do see the point you are making... At louder volumes there will be compression and the volume may be softer than on other speakers. This would make efficient speakers tend to get louder than non-efficient speakers. However, the factor of power handling comes to mind in that there are some "inefficient" speakers that can handle massive amounts of power compared to "efficient" speakers that experience compression with only a small amount of power.

    So doesn't power handling disprove the theory that efficiency determines dynamics? Think about a speaker that has 100db sensitivity with 8 watts power handling (109db). Then compare the dynamics with a speaker that has 90db sensitivity but with 250w power handling (114db).

    Clearly the less sensitive speaker is capable of much greater dynamics.

    I know that a fairly sensitive loud speaker that has enough power handling is capable of outputting far greater volumes due to the cost of high power. Take Pro Audio for example with the sensitive equiptment and good power handling to get very loud.

    What interests me more is microdynamics...

    Manuel's description of microdynamics which was:

     
  13. Manuel Delaflor

    Manuel Delaflor Supporting Actor

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    This thread became interesting! [​IMG]
    What about this? I think microdynamics are better represented by some technologies like horns or electrostats than with regular cone speakers. I say this because I feel more detail is happening with those kind of speakers in the same time unit (so to speak).
    But talking about macrodynamics, I have only listened to one driver that can match the explosiveness of a horn, some ceramic drivers found on some Kharma and Margules speakers.
    I liked the idea of measuring steps of 5dB. One of my own would be to measure the speed of a fast peak in music and how loud it is relatively speaking.
     
  14. David_Stein

    David_Stein Second Unit

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    consider a sine wave playing at a certain volume, then imagine abruptly stopping the signal. its likely that the sound would continue for some minute amount of time. if you could measure the time that it takes for the speaker to stop playing a certain note after the signal stops (and perhaps averaged with the time it takes to start playing sound after starting the signal) wouldnt that be a measure of dynamics? or make it the rate of decay, like db/millisecond or db/microsecond or whatever. i dont know, im not a very educated person in this subject, so basically i just read the thread and tried to think of a way to measure what you are describing.
     
  15. BruceD

    BruceD Screenwriter

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    A 3D waterfall chart (frequency vs SPL over time) can be generated by some acoustic measurement systems today. I use a PC program called EFT5 with a calibrated mic that does this.

    When the mic is at the listening position you are measuring the speaker/room response. You can measure just the speaker with a mic close to the speaker, and the speaker as far away from all walls as possible.

    You can also "window" the response in the FFT analysis that produces the graph to control the time window in milliseconds.
     

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